[PATCH net-next v3 5/6] devlink: hold a reference to the netdevice around ethtool compat

[Jakub Kicinski]

When ethtool is calling into devlink compat code make sure we have
a reference on the netdevice on which the operation was invoked.

v3: move the hold/lock logic into devlink_compat_* functions (Florian)

Signed-off-by: Jakub Kicinski <jakub.kicin...@netronome.com>
---
 net/core/devlink.c | 34 +++++++++++++++++++++++-----------
 net/core/ethtool.c | 13 ++-----------
 2 files changed, 25 insertions(+), 22 deletions(-)

diff --git a/net/core/devlink.c b/net/core/devlink.c
index a13055160be0..78c6ea1870ca 100644
--- a/net/core/devlink.c
+++ b/net/core/devlink.c
@@ -6430,27 +6430,39 @@ void devlink_compat_running_version(struct net_device 
*dev,
 {
        struct devlink *devlink;
 
+       dev_hold(dev);
+       rtnl_unlock();
+
        devlink = netdev_to_devlink(dev);
-       if (!devlink || !devlink->ops || !devlink->ops->info_get)
-               return;
+       if (devlink && devlink->ops && devlink->ops->info_get) {
+               mutex_lock(&devlink->lock);
+               __devlink_compat_running_version(devlink, buf, len);
+               mutex_unlock(&devlink->lock);
+       }
 
-       mutex_lock(&devlink->lock);
-       __devlink_compat_running_version(devlink, buf, len);
-       mutex_unlock(&devlink->lock);
+       rtnl_lock();
+       dev_put(dev);
 }
 
 int devlink_compat_flash_update(struct net_device *dev, const char *file_name)
 {
        struct devlink *devlink;
-       int ret;
+       int ret = -EOPNOTSUPP;
+
+       dev_hold(dev);
+       rtnl_unlock();
 
        devlink = netdev_to_devlink(dev);
-       if (!devlink || !devlink->ops || !devlink->ops->flash_update)
-               return -EOPNOTSUPP;
+       if (devlink && devlink->ops && devlink->ops->flash_update) {
+               mutex_lock(&devlink->lock);
+               ret = devlink->ops->flash_update(devlink, file_name,
+                                                NULL, NULL);
+               mutex_unlock(&devlink->lock);
+       }
+
+       rtnl_lock();
+       dev_put(dev);
 
-       mutex_lock(&devlink->lock);
-       ret = devlink->ops->flash_update(devlink, file_name, NULL, NULL);
-       mutex_unlock(&devlink->lock);
        return ret;
 }
 
diff --git a/net/core/ethtool.c b/net/core/ethtool.c
index 1320e8dce559..47558ffae423 100644
--- a/net/core/ethtool.c
+++ b/net/core/ethtool.c
@@ -805,11 +805,9 @@ static noinline_for_stack int ethtool_get_drvinfo(struct 
net_device *dev,
        if (ops->get_eeprom_len)
                info.eedump_len = ops->get_eeprom_len(dev);
 
-       rtnl_unlock();
        if (!info.fw_version[0])
                devlink_compat_running_version(dev, info.fw_version,
                                               sizeof(info.fw_version));
-       rtnl_lock();
 
        if (copy_to_user(useraddr, &info, sizeof(info)))
                return -EFAULT;
@@ -2040,15 +2038,8 @@ static noinline_for_stack int 
ethtool_flash_device(struct net_device *dev,
                return -EFAULT;
        efl.data[ETHTOOL_FLASH_MAX_FILENAME - 1] = 0;
 
-       if (!dev->ethtool_ops->flash_device) {
-               int ret;
-
-               rtnl_unlock();
-               ret = devlink_compat_flash_update(dev, efl.data);
-               rtnl_lock();
-
-               return ret;
-       }
+       if (!dev->ethtool_ops->flash_device)
+               return devlink_compat_flash_update(dev, efl.data);
 
        return dev->ethtool_ops->flash_device(dev, &efl);
 }
-- 
2.19.2